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光滑和预制裂纹的高温合金试件的应力持久寿命的实验结果说明,预先存在的小裂纹,严重地降低高温合金构件的应力持久强度和寿命。 扫描电镜和金相照片分析说明,裂纹沿晶界孔洞扩展。根据孔洞增长和与主裂纹顶端会合的微观力学分析,用蠕变J积分参量和裂纹张开位移速率推导出蠕变裂纹扩展公式。GH_(33A)高温合金的实验数据论证了上面的断裂力学分析。
Experimental results on the stress-bearing life of smooth and pre-cracked superalloy specimens indicate that pre-existing small cracks severely reduce the stress durability and lifetime of superalloy components. Scanning electron microscopy and metallographic photographs show that cracks propagate along grain boundaries. According to the hole growth and the microscopic mechanical analysis of the convergence with the top of the main crack, the creep crack propagation formula is deduced from the parameters of creep J integral and the crack opening displacement rate. Experimental data of GH_ (33A) superalloy demonstrate the above fracture mechanics analysis.